The pollution of lakes, rivers and costal waters by the unregulated discharge and dumping of industrial, agricultural and municipal wastes has severely damaged the environment. In some cases, the waters have been so seriously impacted that they can no longer support aquatic life or the fish and crustaceans that reside in the waters are no longer safe for human consumption.
The Clean Water Act of 1972 and other similar legislation have established goals for eliminating releases of high amounts of toxic substances into waters and ensuring that surface waters meet certain standards. In addition to limiting the current discharge of pollutants, an effort has been made to remediate lakes, rivers and other bodies of water that have been identified as particularly hazardous to the environment and the health of humans. The remediation can include some form of dredging to remove pollutants that have settled to the bottom of the bodies of water and mixed in with the natural mud and sediments. The amount of material that must be removed can vary from several inches to several feet at different sites. In most cases, the pollutants have migrated so deep into the mud and sediments that it is impractical to entirely remove them. Therefore, dredging is conducted until the pollutants in the dredged materials are determined to be present at a safe level. However, even at safe levels, it is desirable to prevent the pollutants from mixing with the water. Therefore, an aquatic cap material is spread over the bottom of the dredged body of water to act as a barrier between the pollutants in the sediments and the water. In some instances, capping is the only remediation that is required to isolate and trap the pollutants.
The aquatic capping systems that are currently being used do not adequately control the composition of the aquatic capping materials so that it is necessary to deposit a thicker layer of cap material on the bottom of the body of water to ensure that the cap provides a sufficient barrier. In addition, the position of the barge or boat discharging the aquatic capping material and the aquatic cap material discharging apparatus presently being used do not spread a uniform layer of the aquatic capping material on the bottom. This also results in a thicker layer of aquatic capping material being placed on the bottom to ensure a minimum layer thickness. Accordingly, there is a need for an aquatic capping system that can control the composition of the aquatic capping material and provide a layer of aquatic capping material with a highly uniform thickness.